16-2071924-G-T

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM2 PM5 PP3_Strong PP5_Moderate

The NM_000548.5(TSC2):c.2087G>T(p.Cys696Phe) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C696Y) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: TSC2 NM_000548.5 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.28

Genes affected

TSC2 (HGNC:12363): (TSC complex subunit 2) This gene is a tumor suppressor gene that encodes the growth inhibitory protein tuberin. Tuberin interacts with hamartin to form the TSC protein complex which functions in the control of cell growth. This TSC protein complex negatively regulates mammalian target of rapamycin complex 1 (mTORC1) signaling which is a major regulator of anabolic cell growth. Mutations in this gene have been associated with tuberous sclerosis and lymphangioleiomyomatosis. [provided by RefSeq, May 2022]

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr16-2071924-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 50106.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.983
• PP5: Variant 16-2071924-G-T is Pathogenic according to our data. Variant chr16-2071924-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 993650.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TSC2	NM_000548.5	c.2087G>T	p.Cys696Phe	missense_variant	19/42	ENST00000219476.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TSC2	ENST00000219476.9	c.2087G>T	p.Cys696Phe	missense_variant	19/42	5	NM_000548.5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1431658 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 709120

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Mar 09, 2020

The TSC2 c.2087G>T; p.Cys696Phe variant, to our knowledge, is not reported in the medical literature or gene specific databases. This variant is also absent from general population databases (Exome Variant Server, Genome Aggregation Database), indicating it is not a common polymorphism. The cysteine at codon 696 is highly conserved, and computational analyses (SIFT, PolyPhen-2) predict that this variant is deleterious. Additionally, two other variants at this codon (Cys696Arg, Cys696Tyr) are reported in individuals with TSC (Hung 2006, Jones 1999). Functional studies of the Cys696Tyr variant shows it inhibits tuberin-hamartin binding, the tuberin chaperone function and tuberin phosphorylation (Hoogeveen-Westerveld 2011, Nellist 2001). Based on available information, the p.Cys696Phe variant is considered to be likely pathogenic. REFERENCES Hoogeveen-Westerveld M et al. Functional assessment of variants in the TSC1 and TSC2 genes identified in individuals with Tuberous Sclerosis Complex. Hum Mutat. 2011 Apr;32(4):424-35. Hung CC et al. Molecular and clinical analyses of 84 patients with tuberous sclerosis complex. BMC Med Genet. 2006 Sep 18;7:72. Jones AC et al. Comprehensive mutation analysis of TSC1 and TSC2-and phenotypic correlations in 150 families with tuberous sclerosis. Am J Hum Genet. 1999 May;64(5):1305-15. Nellist M et al. TSC2 missense mutations inhibit tuberin phosphorylation and prevent formation of the tuberin-hamartin complex. Hum Mol Genet. 2001 Dec 1;10(25):2889-98. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.47
Cadd	Pathogenic	28
Dann	Uncertain	0.99
DEOGEN2	Pathogenic	0.87	D;.;.;.;.;.;.;.;.;.;.;.;D;.;D
Eigen	Pathogenic	0.76
Eigen_PC	Pathogenic	0.69
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.91	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.37	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.93	D
MutationAssessor	Uncertain	2.8	M;.;.;.;M;M;.;.;.;M;.;M;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D
PrimateAI	Pathogenic	0.91	D
PROVEAN	Pathogenic	-8.2	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
REVEL	Pathogenic	0.87
Sift	Uncertain	0.0070	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Sift4G	Pathogenic	0.0	D;.;.;D;.;D;.;.;D;D;.;.;.;.;D
Polyphen		1.0	D;.;.;.;D;D;.;.;D;D;.;.;.;.;.
Vest4		0.88
MutPred		0.90		Loss of catalytic residue at L697 (P = 0.0245);Loss of catalytic residue at L697 (P = 0.0245);Loss of catalytic residue at L697 (P = 0.0245);.;Loss of catalytic residue at L697 (P = 0.0245);Loss of catalytic residue at L697 (P = 0.0245);Loss of catalytic residue at L697 (P = 0.0245);Loss of catalytic residue at L697 (P = 0.0245);.;Loss of catalytic residue at L697 (P = 0.0245);Loss of catalytic residue at L697 (P = 0.0245);Loss of catalytic residue at L697 (P = 0.0245);Loss of catalytic residue at L697 (P = 0.0245);Loss of catalytic residue at L697 (P = 0.0245);.;
MVP		0.92
ClinPred		1.0	D
GERP RS		5.6
Varity_R		0.94
gMVP		0.76

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs45486196; hg19: chr16-2121925;